1. Field of the Invention
The present invention relates to a semiconductor memory device, and more particularly, it relates to a semiconductor memory device including a spare memory cell repairing a faulty memory cell.
2. Description of the Prior Art
In general, there is a semiconductor memory device having a spare memory cell for repairing a faulty memory cell (hereinafter the term "spare" stands for "redundancy"). Such a conventional semiconductor memory device requires an internal circuit having a programming element for previously programming a faulty address (repair address) indicating a faulty memory cell position. This internal circuit detects that the programmed repair address is input in actual use, thereby using the spare memory cell in place of the faulty memory cell.
The conventional internal circuit uses a fuse blown with a laser beam as the programming element. The fuse serving as the programming element is laser-blown in accordance with the repair address, thereby programming the repair address.
However, a high-priced laser cutter is required for laser blowing with a heavy process burden for the laser blowing, while the blowing accuracy is dispersed. Further, the employment of the laser beam restricts the arrangement of components and wires. When employing the laser blowing, further, the program state may be fixed to restrict the repair efficiency.